Hydrostatic pressure operated apparatus



1 p 1965 J. R. BAKER ETAL 3,203,355

HYDROSTATIC PRESSURE OPERATED APPARATUS Filed Sept. 14, 1960 2Sheets-Sheet 1 INVEN TORS. rib/0v R. BHKE/Q p 1955 J. R. BAKER ETAL.3,208,355

HYDROSTATIC PRESSURE OPERATED APPARATUS Filed Sept. 14, 1960 2Sheets-Sheet 2 v ]NVENTOR5.. Jmv 0 .BHKER 62/7005 fin Muck 3,203,355HYDROSTATTC PRESEURE GPERATED APPARATUi .lohn R. Baker, Pasadena, andClaude A. Houclr, South Pasadena, Calif, assignors to Baker Oil Tools,line,

Los Angeles, Calif., a corporation of California Filed dept. 14, 1960,Ser. No. 87,518 (Filed under Rule 47th) and 35 USJC. 118) Claims. (Cl.91-411) The present invention relates to subsurface well bore equipment,and more particularly to subsurface apparatus for setting well packersand bridge plugs in well bores, and for performing other specificoperations therewithin.

Operations have been undertaken in well bores that require the use of anexplosive, or of a power charge or powder propellant, or both, toinitiate the particular operation or to effect its full performance. Asan example, setting apparatus is disclosed in United States Patent2,640,547, in which a slow burning powder charge or propellant isignited by a cartridge or the like to generate a gas under pressure forthe purpose of operating subsurface Well equipment, such as a bridgeplug or well packer. Although many thousands of operations have beenperformed successfully through use of equipment of the type disclosed inthe aforesaid patent, difliculties are encountered in securing properoperation of the equipment in very hot well bores, as are sometimesencountered in very deep wells (of the order of 18,000 to 20,000 feet),in which the temperatures may be of the order of 400 degrees F. to 450degrees F. The powder charges or propellants, as well as ignitiondevices, like cartridges or a match compound, which are operableproperly at lower temperatures may fail to ignite or may not burnsatisfactorily if ignited because of their deterioration under hightemperature conditions. The result is failure of the operation or itspartial success only.

Accordingly, it is an object of the present invention to provideimproved subsurface apparatus for operating equipment in a well borethat is not adversely affected by very high temperatures that might beencountered in the well bore.

Another object of the invention is to provide a subsurfacehydrostatically operated apparatus for performing an operation in thewell bore, in which the application of hydrostatic pressure to theapparatus is determined by a valve mechanism controlled from the top ofthe well bore.

A further object of the invention is to provide a subsurfacehydrostatically operated apparatus for performing an operation in a wellbore, in which the hydrostatic pressure can shift the valve mechanismthat controls the application of hydrostatic pressure to an opencondition, and in which shifting of the valve mechanism is initiallyresisted by a disruptable device capable of withstanding comparativelyhigh temperatures and forces without deteriorating. In a more limitedsense, the disruptable device includes material capable of burning awayto permit removal of restraint from the valve mechanism and itshydrostatic shifting to open position, the burnable material beingcapable of withstanding high temperatures.

An additional object of the invention is to provide apparatus of thecharacter indicated in which the valve apparatus can move to a fullyopen condition at a relatively slow rate to avoid the imposition ofsudden or shock loads on the equipment by the hydrostatic pressure.

Yet another object of the invention is to provide subsurface fluidpressure operated apparatus for performing an operation in the wellbore, in which the fluid pressure is caused to operate on an improvedtandem arrangement exerted by the apparatus in performing its operation.

States Patent This invention possesses many other advantages and hasother objects which may be made more clearly apparent from aconsideration of several forms in which it may be embodied. Such formsare shown in the drawings accompanying and forming part of the presentspecification. These forms will now be described in detail, for thepurpose of illustrating the general principles of the invention; but itis to be understood that such detailed description is not to be taken ina limiting sense, since the scope of the invention is best defined bythe appended claims.

Referring to the drawings:

FIGURES 1 and 1a are longitudinal sections through an apparatusembodying the invention, FIG. 1a constituting a lower continuation ofFIG. 1, with the parts in their initial position;

FIG. 2 is an enlarged cross section taken along the line 2-2 on FIG. 1;

FIGS. 3 and 3a are longitudinal sections corresponding to FIGS. 1 andla, FIG. 3a constituting a lower continuation of FIG. 3, showing partsof the apparatus in another relative position of operation;

FIG. 4 is a longitudinal section through another embodiment of a portionof the apparatus disposed in FIG. 1 and adapted to be used in theapparatus shown in FIGS. 1 to 3:1, inclusive.

The apparatus particularly illustrated is intended specifically for usein setting a bridge plug or well packer in a well casing or open wellbore. Actually, the lower portion of the apparatus disclosed in FIG. lais connectible to a bridge plug or well packer (not shown) in the samemanner as illustrated in the aforesaid United States Patent 2,640,547.As described in this patent, a piston operated device acts downwardlyupon the upper slips (not shown) of the packer and the cylinder portionof the apparatus exerts an upward force on the body of the well packerapparatus, the opposite direction of movement and the opposite forcesexerted by the piston and cylinder portion of the mechanism effecting afull setting of the plug or packer in the well bore, and also releasingthe setting apparatus from the packer or bridge plug.

As shown in the present drawings, a setting sleeve 10 is slidablymounted on a setting mandrel 11 having a pair of diametrically opposedlongitudinally extending slots 12 therein, through which a cross-overpiece or anvil 13 extends, which is connected to the setting sleeve 10and which passes through the lower end of a piston rod 14 extendingupwardly through a lower cylinder head 15 of a lower cylinder 16. Thehead 15 is threadedly secured to the upper end of the setting mandrel 11and also to the lower end of a lower cylinder sleeve 17. A lower piston18 is piloted over and attached to the upper end of the piston rod 14,as through use of a set screw 19, and is slidable in the lower cylindersleeve 17. Its relative downward movement in the lower cylinder 16 movesthe lower piston rod 14 downwardly, exerting a downward force on thesetting sleeve 10. Reactively, the cylinder 16 moves in an upwarddirection to pull the setting mandrel 11 upwardly, which is releasablyconnected to the body of the well packer or bridge plug (not shown).With the setting sleeve 10 exerting a downward force on the upper slips(not shown) of such bridge plug or well packer and the mandrel 11 anupward force on the packer body, full setting of the bridge plug or wellpacker and release of the setting tool therefrom is accomplished.

The lower piston has side seal rings or piston rings 20 on its peripheryadapted to slidably seal along the wall of the lower cylinder sleeve 17.The lower cylinder head 15 has rod packing or seal rings 21 slidablysealing against the periphery of the piston rod 14. Such seals,accompanied by external seals 22 on the lower cylinder head sealingagainst the wall of the lower cylinder sleeve 17,

provide a confined space 23 in the lower cylinde 16 between the piston18 and lower cylinder head into which the well bore fluid cannot pass,such that this space initially contains air at atmospheric pressure.

The upper end of the lower cylinder sleeve 1'7 is threadedly attached toan intermediate cylinder head 24, which is, in turn, threadedly securedto the lower end of an upper cylinder sleeve forming part of an uppercylinder 26. This upper cylinder sleeve is threadedly secured to anupper head portion 27 of a valve body 23, the upper end of which is, inturn, threadedly attached to a firing head 29 suitably secured, directlyor indirectly, to a wire line (not shown) extending to the top of a wellbore, and which has a conductive element therewithin adapted to conductelectricity to the apparatus, as described hereinbelow.

Disposed in the upper cylinder 26 below its upper head 27 is an upperpiston 30 which is threadedly or otherwise suitably secured to a tubularthrust rod or upper piston rod 31 that extends downwardly through theupper cylinder sleeve 25 and through the central bore 32 in theintermediate cylinder head 24, the lower end of the tubular rod 31engaging the upper end of the lower piston 18. The upper end of theupper piston 30 has an inlet port 33 for allowing fluid under pressureto pass downwardly through the central passage 34 in the upper pistonrod, such fluid then passing outwardly through an outlet port 35 in thelower portion of the tubular rod into the lower cylinder 16 above thelower piston 13. Leakage of fluid around the upper piston 30 isprevented by suitable piston rings 36 mounted in its peripheral portionand slidably sealing against the wall of the upper cylinder sleeve 25.Similarly, rod packing 37 is mounted in the intermediate cylinder head24 which is adapted to slidably seal against the upper piston rod orthrust rod 31, thereby providing an upper confined cylinder space 38between the upper piston 30 and the intermediate cylinder head 24 intowhich the well bore fluid cannot pass, this upper confined cylinderspace initially containing air at substantially atmospheric pressure.Leakage of fluid between the intermediate cylinder head 27 and uppercylinder sleeve 25 is prevented by suitable side seal rings 39 mountedon the intermediate cylinder head and engaging the inner wall of theupper cylinder sleeve. Similarly, leakage of fluid between the upperhead 27 and the upper cylinder sleeve 25 is prevented by suitable sideseal rings 40 mounted in the upper head and engaging the wall of theupper cylinder sleeve 25.

Initially, the lower and upper pistons 30, 18 are located in the upperportions of the lower and upper cylinders 26, 16, respectively. Inasmuchas the apparatus is intended for use in a well bore containing fluid,the pistons are to be shifted relatively downwardly in thei respectivecylinders by the fluid under hydrostatic pressure externally of theapparatus. Such fluid under hydrostatic pressure, when permitted to doso, can pass through lateral inlet ports 42 to the central passage orcylinder 43 of the valve body, then passing downwardly through thecentral passage 44 in a valve guide 45 threadedly secured in the uppercylinder head 27 into the upper cylinder 26 for downward action upon theupper piston 30. The fluid under hydrostatic pressure will also passthrough the upper inlet port 33 into the central passage 34 through theupper piston rod 31, and out through its outlet port 35 into the lowercylinder 16 for downward action upon the lower piston 18. The upper andlower pistons 30, 18 move downwardly toegther to exert their combinedforce on the lower piston rod 14 and through the cross-over piece 13 onthe setting sleeve 10 surrounding the setting mandrel 11.

The fluid under hydrostatic pressure also acts upwardly over theeflective cross-sectional areas of the upper and intermediate cylinderheads 27, 24, to exert a combined force on the lower cylinder sleeve 17and lower cylinder head 15, which is transmitted to the setting mandrel11,

urging it in an upward direction and thereby exerting the upward pull onthe well packer or plug body (not shown). Since the well bore fluidcannot enter the confined upper cylinder space 38 below the upper piston30 and the confined lower cylinder space 23 below the lower piston 18,the undersides or" these pistons have only air at substantiallyatmospheric pressure, or slightly above such pressure as the pistonsmove downwardly, acting upon them, whereas the hydrostatic forces actingon the upper sides of the upper and lower pistons is proportional to thehydrostatic head of fluid externally of the equipment. If, for example,the apparatus is used in a very deep well, with the setting operationbeing performed at about 20,000 feet below the top of the well bore, theunit hydrostatic pressure available for action on the upper and lowerpis tons 30, 18 will be of the order of about 10,000 psi. Suchrelatively high pressures operating over the substantial areas of theupper and lower pistons makes a very great total setting force availablefor the appropriate setting or operation of the equipment secured to thelower portion of the apparatus illustrated.

Operation of the apparatus until it has been lowered to the desireddepth in the well bore is prevented by maintaining the inlet ports 42 ina closed condition, so that the hydrostatic head of fluid cannot enterthe cylinders 26, 16 for action upon the pistons 30, 18 and the cylinderheads 27, 24. As disclosed, the ports are closed by a differential valverod or piston 47. The lower portion 48 of the rod below the inlet ports42 is disposed within the valve guide 45 and has a suitable seal ring49, such as a rubber or rubber-like O ring, in a ring groove 50, sealingagainst the inner wall of the guide to prevent passage of fluid pressuredownwardly through the guide and into the cylinders 26, 16 therebelow.The hydrostatic fluid under pressure is prevented from passing in anupward direction through an upper cylinder or central passage 51 thatopens into an enlarged release chamber 52 in the valve body 28. Theupper portion 53 of the valve rod is adapted to slidably seal in thecentral cylinder 51, leakage of fluid between the rod and the cylinderwall being prevented by a suitable side seal ring 54, such as a rubberor rubberlike 0 ring, disposed in a peripheral groove 55 in the valverod and engaging the cylinder wall 51 above the inlet port.

The upper portion 53 of the valve rod 47 is constituted as a pistonhaving a larger diameter, and preferably only slightly larger, than thediameter of a smaller piston portion 48 that slides in the lower guide45. Because of the difference in areas between the upper and lowerpiston portions 53, :3 of the valve on opposite sides of the inlet ports42, the hydrostatic head of fluid is acting in an upward direction overthe outer annular part 56 of the large piston and tends to shift suchlarge piston 53 in an upward direction within its cylinder 51.

When the valve rod 47 is permitted to move upwardly, the lower seal ringmoves upwardly out of the guide 45, whereupon the hydrostatic fluidunder pressure can then pass from the inlet ports 42 into a longitudinalgroove or flute 57 running along the external portion of the valve rodbelow its seal ring 19, and into the cylinder 26 there below. The singlegroove 57 is provided so that the fluid under pressure can only pass ata relatively slow rate into the cylinders 26, 16, to avoid theimposition of sudden or shock loads on the apparatus. The valve rod 47can shift upwardly to an extent at which its lower end is disposed abovethe ports, then providing a full opening for the hydrostatic fluid underpressure to pass into the central guide 45 and then into the cylinders2s, 16 for action upon the upper and lower pistons 30, 18, in the mannerdescribed above.

It is to be noted that the valve rod 47 extends upwardly from the largerpitson 53 through the cylinder 51 and projects into the release chamber52. This release chamber has a retainer or holding device 60 which atfirst is engaged by the upper end of the valve rod 47 to prevent thelatter from moving upwardly to a position opening the inlet ports 42.When the retainer or holding device 60 is released, then the hydrostatichead of fluid moves the valve rod 47 upwardly. However, such upwardmotion is retarded by filling the annular space 61 between the upperportion 62 of the valve rod and the cylinder wall Sll with grease 63,requiring the upper piston 53 to force such grease through a relativelysmall annular orifice 64 at the entrance to the release chamber 52,provided by decreasing the internal diameter of the cylinder at itsupper portion. Such smaller internal diameter is only slightly greaterthan the external diameter of the upper portion 62 of the valve rod. Thenecessity for the grease to be forced through the annular orifice 64 andinto the release chamber 52 retards the rate at which the valve rod 47can be shifted upwardly by the hydrostatic head of fluid to a fullyopened position, thereby allowing time for the fluid to pass through therelatively narrow area flute or groove 57 in the lower portion of thevalve rod and into the cylinder 26, in order to gradually build up thepressure in the upper and lower cylinders 26, 16 for action upon theupper and lower pistons 3t), 18 and the upper and intermediate cylinderhead 27, 24.

Upward movement of the valve rod 47 by the hydrostatic head of fluid isat first prevented by a material which is capable of beingdisintegrated. As shown, a substantially cylindrical casing 65 isdisposed coaxially in the release chamber 52, the upper end of thiscasing being secured to a head 66 which is, in turn, attached to asleeve 67 threadedly secured to the firing head 29. The retainer head 66is attached to the sleeve 67 by a set screw 68, or the like. The casingor tubular retainer member 65 has a plurality of perforations 69extending through its wall and contains a material 70 that is capable ofburning away. Prior to its ignition and burning away, this material 76has substantial compressive strength, and is well capable of resistingrelatively large hydrostatic heads of fluid tending to shift the valverod 47 in an upward position. As shown, the material 76 fills the casing65, being formed as a plurality of superimposed collars or discs, thelower one of which engages the upper end of the valve rod 47, the upperone of which engaging the retainer head 66 which, in turn, bears againsta downwardly facing shoulder 71 of the sleeve 67. As a result, upwardforce on the valve rod 47 is transmitted through the pellets or discs70, through the head 66 and thence through the sleeve 67, which isconnected through the firing head 29 to the valve body 28. Accordingly,the valve rod 4'7 cannot shift upwardly at this time. For convenience ofassembly, the valve rod may be prevented from dropping from the retainercasing 65 by a flange 72 on the upper end of the rod engaging aninwardly directed shoulder 73 therebelow constituting the lower end ofthe casing 65.

When the proper depth in the well bore is reached at which the apparatusis to be operated, the material 769 within the casing 65 is ignited andwill either burn or melt away, flowing outwardly through theperforations 69 into the release chamber 52, which contains air atsubstantially atmospheric pressure. Leakage of fluid into this chamberfrom the exterior of the apparatus is prevented by the seal ring 54 onthe upper valve rod piston 53 and also by side seals 74 on the sleeve engaging the adjacent wall of the valve body 28 and the adjacent wall ofthe firing head 29. As the material 76 burns away or melts, the productsof combustion or the molten material itself flows out through theperforations 69 into the chamber 52. The hydrostatic head can then forcethe valve rod 47 upwardly into the cylinder 51, the upper portion 62 ofthe rod then moving into the casing 65.

The material 76 in the casing can be ignited by providing a suitableigniter or match compound 75 in the head. This igniter or match compoundhas a suitable filament (not shown), one end of which is grounded,

the other end of which making contact with a conductor rod '76 extendinginto the sleeve 67 and insulated therefrom by a suitable surroundinginsulating sleeve 77. The upper end of this rod 76 engages a conductiveterminal 73 extending through an insulating washer 79 held in placewithin the firing head 29 by a suitable threaded nut 80. The conductiveterminal 78 is engaged by a conductive coil spring 81 which engages aconductor rod 82, the terminal spring and rod being contained within aninsulating sleeve 83 in the central firing head passage 84. Theconductor rod 82 is connected in a known manner to the centralconductive core of a wire line (not shown), which is attached directlyor indirectly to the firing head, in a known manner.

When current is caused to pass downwardly through the conductive wireline and the several conductive elements 82, 81, 78, 76 to the igniteror match compound 75, the latter is ignited and will initiate combustionof the adjacent material 70 in the casing 65. Such material either burnsaway or assumes a molten state, whereby the valve rod 47 is movedupwardly by the hydrostatic head of fluid in the casing, bringing theflute or passage 57 in the valve rod 47 below its seal 49 incommunication with the inlet ports 42, allowing the hydrostatic head offluid to enter the cylinders 26, 16 for action upon the pistons 36, 18and set the bridge plug, well packer, or the like, connected to thesetting tool. The fluid pressure effects a full setting of the equipmenttherebelow, and its release from the setting tool in a known manner, asmore specifically described in the aforesaid United States Patent2,640,547.

The pellets or discs 70 are preferably made of a material which is notadversely effected by relatively high temperatures encountered in somewell bores, which, as indicated above, may be of the order of 400 to 450degrees F. One such material is a photoflash mixture. For example, itmay consist of 55% by weight of mag nesium, 36% by weight of sodiumnitrate, which functions as an oxidizer, and about 9% by weight of aresin binder. Another material that can be used is that found inincendiary bombs, which may consist of 48% by weight of a 5050magnesium-aluminum alloy and 52% by weight of barium nitrate.

The material just referred to, when ignited, will burn away and will notbe available for the offering of resistance to upward movement of thevalve rod 47 in the valve body 26. However, such materials havesufficient compressive strength prior to ignition to prevent upwardmovement of the valve rod from its position closing the inlet ports 42.

In lieu of the materials just referred to, a thermite material can beused in the casing, which consists of a mixture of aluminum and ferricoxide. When ignited by the match compound 75, such material will meltand will flow through the perforations 69 into the release chamber 52surrounding the casing 65, its ejection through the perforations in thecasing being aided by the fact that the rod 47 is being urged upwardlyby the hydrostatic head of fluid externally of the apparatus.

The aforenoted materials prior to ignition all have ample compressivestrength to prevent the rod 47 from being moved upwardly. It is onlyupon their ignition that they will either burn to a gaseous form andpass through the perforations 69 into the release chamber 51, permittingupward movement of the rod in the casing 65, or they will develop asufliciently high temperature as to melt (like the thermite material),then flowing out through the perforations 69, being assisted in suchmovement by the upward passage of the valve rod 47 into the perforatedcasing 65.

The form of invention disclosed in FIG. 4 can be employed in the releasechamber 52 in lieu of the perforated casing and the material containedtherewithin. As shown, a frangible valve retainer or holder 90, which,for example, may be made of cast iron, extends upwardly into the sleeve67, bearing against the shoulder 71 and being retained in place by a setscrew 68, or the like. This frangible housing or retainer 969 extendsdownwardly within the release chamber 51 to substantially the sameextent as the perforated casing 65 illustrated in FIGS. 1 and 3, thelower end of the housing 90 being closed and engaging the upper end ofthe valve rod 4-7. Thus, the frangible retainer J ll, by engaging therod, prevents the latter from moving upwardly to a position opening theinlet ports 42.

Contained within the hollow housing or retainer 90 is a blasting cap 91capable of withstanding comparatively high temperatures, which, forexample, may be of the order of 500 degrees F. This blasting cap iselectrically connected to the conductor rod 76 through an interveningcontact 92 and conductive wiring 93, one wire being grounded.

'When the proper location in the well bore is reached at which theapparatus is to be operated, the electric circuit through the blastingcap 91 is completed, the latter exploding and shattering the frangiblehousing 90, the pieces thereof then moving freely into the releasechamber 52, which is of a substantially greater diameter than theoutside diameter of the frangible retainer itself. As a result,restraint to upward movement of the valve rod 47 is removed and thehydrostatic head can then shift the latter upwardly to a positionopening the inlet ports 42, thereby permitting operation of theapparatus in the manner described above.

We claim:

1. In apparatus adapted to be disposed in a well bore: upper and lowercylinders secured together; lower piston means in said lower cylinderand having a portion extending outwardly therefrom; upper piston meansin said upper cylinder and having a portion extending outwardlytherefrom into said lower cylinder in engagement with said lower pistonmeans; means preventing entry of well bore fluid externally of saidcylinders into said cylinders below said upper and lower piston means;said upper and lower cylinders containing a gaseous medium below saidupper piston means and lower piston means, respectively, when disposedin a well bore containing a surrounding liquid; means for conductingwell bore fluid under pressure from the exterior of said upper cylinderinto said upper cylinder for direct action upon the upper side of saidupper piston means to shift said upper piston means relativelydownwardly in said upper cylinder; means for conducting such fluid underpressure from said upper cylinder into said lower cylinder for actionupon the upper side of said lower piston means to shift said lowerpiston means relatively downwardly in said lower cylinder; valve meansabove and separate from said upper piston means initially closing saidwill bore fluid conducting means to prevent well bore fluid from beingexerted upon any and all portions of said upper i piston means; andmeans for shifting said valve means in a direction away from said upperpiston means to open position.

2. In apparatus adapted to be disposed in a well bore: upper and lowercylinders secured together; lower piston means in said lower cylinderand having a portion extending outwardly therefrom; upper piston meansin said upper cylinder and having a portion extending outwardlytherefrom into said lower cylinder in engagement with said lower pistonmeans; means preventing entry of well bore fluid externally of saidcylinders into said cylinders below said upper and lower piston means;said upper and lower cylinders containing a gaseous medium below saidupper piston means and lower piston means, respectively, when disposedin a well bore containing a surrounding liquid; means for conductingwell bore fluid under pressure from the exterior of said cylinder intosaid upper cylinder for direct action upon said upper piston means;means for conducting such fluid under pressure from said upper cylinderinto said lower cylinder for action upon said lower piston means; valvemeans above and separate from said upper piston means initially closingsaid well bore fluid conducting means to prevent well bore fluid frombeing exerted upon any and all portions of said upper piston means;means responsive to fluid pressure externally of said upper cylinder forshifting said valve means in a direction away from said upper pistonmeans to open position; means preventing such shifting of said valvemeans; and means for releasing said preventing means.

3. In apparatus adapted to be disposed in a well bore: cylinder means;piston means in said cylinder means; means for conducting fluid underpressure into said cylinder means for action upon said piston means;valve means initially closing said conducting means to prevent passageof fluid under pressure into said cylinder means for exertion upon anyand all portions of said piston means; means associated with said valvemeans and responsive to the pressure of fluid in the well bore forshifting said valve means to open position in a direction away from saidpiston means; means engageable with said valve means to prevent shiftingof said valve means to open position under the action of fluid pressure;and means for releasing said preventing means to permit said shiftingmeans to shift said valve means to open position under the action of thefluid pressure.

4. In apparatus adapted to be disposed in a well bore: cylinder means;piston means in said cylinder means; means for conducting fluid underhydrostatic pressure externally of said cylinder means into saidcylinder means for action upon said piston means; valve means initiallyclosing said conducting means to prevent said fluid under eX- ternalhydrostatic pressure from being exterted upon any and all portions ofsaid piston means; means associated with said valve means and exposed toand responsive to hydorstatic fluid pressure externally of said cylindermeans for shifting said valve means to open position in a direction awayfrom said piston means; disruptable means for preventing such shiftingof said valve means; and means for disrupting said disruptable means topermit such shifting of said valve means.

5. In apparatus adapted to be disposed in a well bore: cylinder means;piston means in said cylinder means; means for conducting fluid underhydrostatic pressure externally of said cylinder means into saidcylinder means for action upon said piston means; valve means initiallyclosing said conducting means to prevent said fluid under externalhydrostatic pressure from being exerted upon any and all portions ofsaid piston means; said valve means having a portion providing adifferential area subject to hydrostatic fluid pressure externally ofsaid cylinder means tending to shift said valve means to open positionin a direction away from said piston means; disruptable means engagingsaid valve means for preventing such shifting of said valve means; andmeans for disrupting said disruptable means to permit such shifting ofsaid valve means.

6. In apparatus adapted to be disposed in a well bore: cylinder means;piston means in said cylinder means; means for conducting fluid underhydrostatic pressure externally of said cylinder means into saidcylinder means for action upon said piston means; valve means initiallyclosing said conducting means to prevent said fluid under externalhydrostatic pressure from being exerted upon any and all portions ofsaid piston means; means associated with said valve means and exposed toand responsive to hydrostatic fluid pressure externally of said cylindermeans for shifting said valve means to open position in a direction awayfrom said piston means; combustible means engaged by said valve meansfor pre venting such shifting of said valve means; and means forigniting said combustible means to effect its burning and to removerestraint from said valve means whereby said valve means is shiftable toopen position.

'7. In apparatus adapted to be disposed in a well bore:

cylinder means; piston means in said cylinder means; means forconducting fluid under hydrostatic pressure externally of said cylindermeans into said cylinder means for action upon said piston means; valvemeans initially closing said conducting means to prevent said fluidunder external hydrostatic pressure from being exerted upon any and allportions of said piston means; means associated with said valve meansand exposed to and responsive to hydrostatic fluid pressure externallyof said cylinder means for shifting said valve means to open position ina direction away from said piston means; frangible means engaged by saidvalve means for preventing such shifting of said valve means; andexplosive means for disrupting said frangible means to remove restraintfrom said valve means whereby said valve means is shittable to openposition.

8. In apparatus adapted to be disposed in a well bore: cylinder means;piston means in said cylinder means; means for conducting fluid underhydrostatic pressure externally of said cylinder means into saidcylinder means for action upon said piston means; valve means slidablein and initially closing said conducting means; means providing arelease chamber into which said valve means is adapted to move; saidvalve means having a portion providing a ditferential area subject tohydrostatic fluid pressure externally of said cylinder means tending toshift said valve means into said release chamber and to open position;disruptable means in said release chamber engaged by said valve meansfor preventing shifting of said valve means to open position; and meansfor disrupting said disruptable means to permit shifting of said valvemeans into said release chamber and to open position.

9. In apparatus adapted to be disposed in a well bore: cylinder means;piston means in said cylinder means; means for conducting fluid underhydrostatic pressure externally of said cylinder means into saidcylinder means for action upon said piston means; valve means slidablein and initially closing said conducting means; means providing arelease chamber into which said valve means is adapted to move; saidvalve means having a portion providing a differential area subject tohydrostatic fluid pressure externally of said cylinder means tending toshift said valve means into said release chamber and to open position;combustible means in said release chamber engaged by said valve meansfor preventing shifting of said valve means to open position; and meansfor igniting said combustible means to effect its burning in saidchamber and to remove restraint from said valve means to permit shiftingof said valve means into said release chamber and to open position.

10. In apparatus adapted to be disposed in a well bore: cylinder means;piston means in said cylinder means; means for conducting fluid underhydrostatic pressure externally of said cylinder means into saidcylinder means for action upon said piston means; valve means slidablein and initially closing said conducting means; means providing arelease chamber into which said valve means is adapted to move; saidvalve means having a portion providing a ditterential area subject tohydrostatic fluid pressure externally of said cylinder means tending toshift said valve means into said release chamber and to open position;frangible means in said release chamber engaged by said valve means forpreventing shifting of said valve means to open position; and means fordisrupting said frangible means to permit shifting of said valve meansinto said release chamber and to open position.

References Cited by the Examiner UNITED STATES PATENTS 2,279,676 4/42Hart 166--63 2,308,004 1/43 Hart 16663 2,377,249 5/45 Lawrence 166-982,595,014 4/52 Smith et al 16698 2,807,325 9/57 Webb 16663 2,815,81612/57 Baker 166-63 2,829,716 4/58 Stewart 16698 2,978,028 4/61 Webb166*63 2,979,904 4/61 Royer 166123 3,125,162 3/64 Briggs et al. 166-423BENJAMIN HERSH, Primary Examiner. BE J M N BENDE a i r,

1. IN APPARATUS ADAPTED TO BE DISPOSED IN A WELL BORE: UPPER AND LOWERCYLINDERS SECURED TOGETHER; LOWER PISTON MEANS IN SAID LOWER CYLINDERAND HAVING A PORTION EXTENDING OUTWARDLY THEREFROM; UPPER PISTON MEANSIN SAID UPPER CYLINDER AND HAVING A PORTION EXTENDING OUTWARDLYTHEREFROM INTO SAID LOWER CYLINDER IN ENGAGEMENT WITH SAID LOWER PISTONMEANS; MEANS PREVENTING ENTRY OF WELL BORE FLUID EXTERNALLY OF SAIDCYLINDERS INTO SAID CYLINDERS BELOW SAID UPPER AND LOWER PISTON MEANS;SAID UPPER AND LOWER CYLINDERS CONTAINING A GASEOUS MEDIUM BELOW SAIDUPPER PISTON MEANS AND LOWER PISTON MEANS, RESPECTIVELY, WHEN DISPOSEDIN A WELL BORE CONTAINING A SURROUNDING LIQUID; MEANS FOR CONDUCTINGWELL BORE FLUID UNDER PRESSURE FROM THE EXTERIOR OF SAID UPPER CYLINDERINTO SAID UPPER CYLINDER FOR DIRECT ACTION UPON THE UPPER SIDE OF SAIDUPPER PISTON MEANS TO SHIFT SAID UPPER PISTON MEANS RELATIVELY DOWNWARDIN SAID UPPER CYLINDER; MEANS FOR CONDUCTING SUCH FLUID UNDER PRESSUREFROM SAID UPPER CYLINDER INTO SAID LOWER CYLINDER FOR ACTION UPON THEUPPER SIDE OF SAID LOWER PISTON MEANS TO SHIFT SAID LOWER PISTON MEANSRELATIVELY DOWNWARDLY IN SAID LOWER CYLINDER; VALVE MEANS ABOVE ANDSEPARATE FROM SAID UPPER PISTON MEANS INITIALLY CLOSING SAID WILL BOREFLUID CONDUCTING MEANS TO PREVENT WELL BORE FLUID FROM BEING EXERTEDUPON ANY AND ALL PORTIONS OF SAID UPPER PISTON MEANS; AND MEANS FORSHIFTING SAID VALVE MEANS IN A DIRECTION AWAY FROM SAID UPPER PISTONMEANS TO OPEN POSITION.